Light stabilizers enhance color protection during curing process

Waterborne UV curable coatings – Eco-Friendly coatings - have been developed to replace conventional UV curable coatings with VOC emissions. The challenges of waterborne UV curable coatings have two aspects. One is discoloration may occur when resins are exposed to Ultra Voilet (UV) light radiation from natural sunlight. Waterborne UV-curable light stabilizers are applied to the surface for protection. The other is yellowing during curing process. This problem will affect customer’s product quality and therefore increase product costs.

 

The novel light stabilizer (NLS) is developed specifically for waterborne UV curable coats to reduce yellowing during curing process. In a study conducted by experts from Everlight Chemical Industrial Corporatio, test data showed that the NLS in a waterborne clear UV curable coating would not have negative impacts to cure speed. The results confirmed that by increasing the concentration of NLS in the top coat can effectively reduce yellowing during curing process. Furthermore, data also showed that by increasing the coating thickness, the yellowing during curing process can not be improved to some degrees.

    

UV curing processes have been used extensively in many different industries such as packaging, printing inks and protective coatings for wood, plastics and metal etc. However the UV curable coatings are having odor, emission monomers and not zero VOC emission. In the other hand, the UV curable waterborne coating has both the advantages of waterborne coating and UV curable coating such as non toxic, pollutionfree, and safety in use. In recent years the research and development has grown faster. 

    

In dry faster system, UV curable coatings play up important role to this system. Light stabilizers package can be including UV absorbers (UVA) and hinder amine light stabilizers (HALS) are known to prevent coating damages caused by UV irradiation. In the other hand, photo initiator absorbs UV energy to initiate curing processes. UV absorber absorbs UV energy to prevent coatings damages. As a result, UV absorber and photo initiator are competing to each other for UV energy and create a negative impact to the cure speed. 

 

In the study released by Everlight, the company demonstrates its recent development on liquid NLS for waterborne UV-curable coating with objectives to effectively reduce yellowing during curing process and eliminate negative impacts to the curing speed. 

    

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